This invention pertains to screwdriver bits adapted to fit in the chuck of a power driver, quick release chuck or the like, and more particularly to a bit having an operative screwdriver tip on each end.
Screwdriver bits having a hexagonal shank and configured to be held in standard chucks have been known for many years. They are often referred to as xe2x80x9cpower bits.xe2x80x9d Such bits have a circumferential groove and are sized to fit in chucks with a hexagonal bore and having a ball which fits into the circumferential groove in the shank of the bit, locking and holding the bit in place in the chuck. A quick release chuck for this purpose is shown, for example, in U.S. Pat. No. 4,692,073 Martindell.
The standard for such prior art bits is specified by the American National Standards Institute in ANSI B107.4-1982, setting out the dimensions that make the bits compatible with standard chucks. The single circumferential groove in such bits typically has a flat portion mid way between two equal radiused portions. For xc2xc inch bits, i.e. bits having a shank height of 0.248-0.250 inches, (measured across opposed flat sides) the flat portion of the groove is {fraction (1/16)} inch wide and the distance from the adjacent flat end of the bit is {fraction (11/32)} inch. The distance from the midpoint of the flat portion of the groove to the adjacent flat end of the bit is accordingly xe2x85x9c inch. This is the standard length that permits the bit to be fully seated in the bore of the chuck with the ball of the chuck fitted against the circumferential groove of the bit.
Screwdriver bits of this type in the prior art are single-ended, i.e. having a screwdriver tip at only one end, the other end being flat and, in use, seated against the base of the bore of the chuck. A separate bit is required for each different size or type of fastener head.
It is desirable for screwdriver bits to be two-ended, with each end being adapted to fit a different size or type of fastener head, in order to halve the number of bits required in a set of tools, thus reducing cost and required storage space. Two-ended screwdriver bits are known, but not ones adapted to fit in a standard chuck of the type described above, that accepts standard bits complying with ANSI B107.4-1982.
I have invented a two-ended screwdriver bit that is compatible with standard chucks of the type that are adapted to receive a xc2xc inch hexagonal bit having only a single screwdriver tip and that require a length of xe2x85x9c inch between the end of the bit that seats in the chuck and the midpoint of the groove that receives the ball of the chuck; at the same time, my screwdriver bit has tips large enough to fit properly in fastener heads of the sizes that are commonly turned with xc2xc inch hex bits. Surprisingly, the length of the essential, functional part of the screwdriver tip that is required in order to fully engage a recess in a fastener head can be made substantially shorter than in prior art screwdriver bits. Also, the end portion of the hexagonal shank of the bit, that is the portion between the circumferential groove and the end of the screwdriver that abuts the base of the chuck bore, can be made much shorter than in prior art screwdriver bits while remaining capable of providing a secure fitting of the hexagonal shank within the chuck. The combination of these two reductions in length of these components makes possible a two-ended bit having tips of a size that engage fully in the recesses of common fastener head sizes and which fits and is functionally compatible with chucks that accept standard xc2xc inch hexagonal bits complying with ANSI B107.4-1982.
My invention provides a two-ended screwdriver bit which fits in chucks that accept xc2xc inch hexagonal bits complying with ANSI B107.4-1982, such that either end of the screwdriver bit can be seated and locked in the chuck with the opposite end in the operative position for turning a fastener. The screwdriver bit has a hexagonal shank having a nominal height of xc2xc inch, two circumferentially-extending grooves in the shank, one adjacent to each end and dividing the shank into a relatively long middle portion and two relatively short end portions, a screwdriver tip extending from each end of the shank, each tip having a free outer end, each of the grooves having a longitudinal midpoint, and the longitudinal distance between the outer end of each tip and the longitudinal midpoint of its adjacent circumferential groove being about xe2x85x9c inches.
In one embodiment of the invention, the bit has screwdriver tips shaped to fit a standard Phillips cross-shaped recess of a fastener. The diameter of the tips is at least 0.08 inches.
According to a second embodiment of the invention, the screwdriver bit has tips shaped to fit a standard square-shaped recess of a fastener. The width of the tips between opposite faces thereof is at least 0.06 inches.
In a third embodiment, the screwdriver bit has tips shaped to fit a standard slot-shaped recess of a fastener. The width of the tips of such bits is at least 0.1 inches.
In a fourth embodiment, the screwdriver bit has tips shaped to fit a standard hexagonal-shaped recess of a fastener. The width of the tips between opposite faces thereof is at least {fraction (1/16)}th inch.
In a fifth embodiment, the screwdriver has tips shaped to fit a standard six-point star-shaped recess of a fastener. The width of the tips between opposite points of the star is at least 0.11 inches.